How to inspect a dryer's idler pulley wheel:

Inspecting an idler pulley wheel

Note:

Disconnect the power source to your dryer before you conduct this or any other inspection. Either unplug the unit from the wall outlet, remove the appropriate fuse from the fuse box, or flick the appropriate breaker in the circuit breaker panel.

A dryer's idler pulley wheel serves to help the belt to rotate the drum. If it becomes worn, or if it breaks, then the drum will be impeded in its attempts to tumble and rotate. Inspect your dryer's idler pulley wheel and idler pulley arm. If it is excessively worn, has little cracks, or is broken altogether, you will have to replace it.

With your dryer opened up, you'll notice that the belt loops over the drum, under the idler pulley wheel, and around the motor's drive pulley. Tension is applied to the belt by the idler pulley wheel that sits on a moveable arm.

You can now reach into your dryer, to the belt. Be weary of any sharp edges on the inside of the cabinet and the interior supports. Tug on the belt. Is should be tight, with only a little give when you tug on it. Push the idler pulley towards the motor so that you can release the tension on the belt. Now you can remove the belt and inspect the idler pulley wheel.

Look closely at the pulley wheel. Take note if it is noticeably damaged, or if it is no longer maintaining the required tension. Spin the pulley wheel. It should turn smoothly and quietly, without any wobble. If your dryer's idler pulley wheel assembly is damaged, excessively worn, or no longer functioning as it should, it will have to be replaced. Depending on your dryer model, you may be able to replace just the wheel, or the entire idler pulley wheel and idler pulley arm assembly.